Intravascular flow diverter and related methods

ABSTRACT

An intravascular flow diverter for treating an aneurysm of a blood vessel is provided. The intravascular flow diverter includes a stent including a plurality of wires coiled to form an expandable structure. The intravascular flow diverter includes a cover disposed on at least a portion of the outer surface of the device. The cover includes a first portion configured to be disposed directly against a neck of the aneurysm. The membrane includes at least one second portion configured to be disposed adjacent to and not directly over the aneurysm. The first portion has a first porosity to blood flow, and the second portion has a second porosity to blood flow greater than the first porosity. Related methods of use and manufacturing are also provided.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Applications 63/313,487 and 63/313,635, both filed on Feb. 24, 2022. The entire disclosures of these applications are hereby incorporated by reference in their entireties.

BACKGROUND

Intracranial aneurysms are among the most serious of medical conditions. Their typical size and location make them especially difficult to detect and treat; but even small ones, if ruptured, can cause debilitating physical and cognitive impairment, coma, and death. Initial treatment methods involved clip ligation of the neck of the aneurysm in open surgical procedures. More recently, minimally invasive endovascular techniques have been developed. Given the clinical significance of the condition and the difficulties encountered in addressing it, treatment for intracranial aneurysms remains an especially active area of device and surgical procedure development.

It should be noted that this Background is not intended to be an aid in determining the scope of the claimed subject matter nor be viewed as limiting the claimed subject matter to implementations that solve any or all of the disadvantages or problems presented above. The discussion of any technology, documents, or references in this Background section should not be interpreted as an admission that the material described is prior art to any of the subject matter claimed herein.

SUMMARY

In one embodiment, an intravascular flow diverter for treating an aneurysm of an intracranial blood vessel comprises one or more wires forming a frame, wherein the frame has a collapsed configuration and an expanded configuration, wherein the frame is configured to transition in use from the collapsed configuration to a deployed configuration that substantially conforms to a shape of an inside surface of the intracranial blood vessel in the vicinity of the aneurysm. The flow diverter further comprises an electrospun cover disposed on at least a portion of the frame. The cover comprises a first portion configured to be disposed against a neck of the aneurysm, the first portion of the cover having pores formed therein defining a first porosity thereof and a second portion having a second porosity to blood flow greater than the first porosity, wherein the second portion is configured to be disposed adjacent to and not directly over the aneurysm.

In another embodiment, an intravascular flow diverter for treating an aneurysm of an intracranial blood vessel comprises one or more wires forming a frame, wherein the frame has a collapsed configuration and an expanded configuration, wherein the frame is configured to transition in use from the collapsed configuration to a deployed configuration that substantially conforms to a shape of an inside surface of the intracranial blood vessel in the vicinity of the aneurysm. The flow diverter further comprises an electrospun cover disposed on at least a portion of the frame. The cover comprises a first portion configured to be disposed against a neck of the aneurysm, the first portion of the cover having pores formed therein defining a first porosity thereof, a second portion distal to the first portion having a second porosity to blood flow greater than the first porosity, wherein the second portion is configured to be disposed adjacent to and not directly over the aneurysm, and a third portion proximal to the first portion having a third porosity to blood flow greater than the first porosity, wherein the third portion is configured to be disposed adjacent to and not directly over the aneurysm. In this embodiment, each of the one or more wires has a diameter of less than 0.002 inches, wherein the frame porosity over substantially the whole length of the frame is at least 93% in an expanded frame configuration, wherein the first porosity is less than 0.05 and the second porosity and the third porosities are each greater than 0.05.

In another embodiment, a method of using an intravascular flow diverter to treat an aneurysm of an intracranial blood vessel comprises disposing the intravascular flow diverter within a microcatheter, threading the microcatheter through the intracranial blood vessel to a location of the aneurysm and removing the intravascular flow diverter from a distal end of the microcatheter such that a stent of the intravascular flow diverter, comprising a plurality of wires coiled to form an expandable structure, expands sufficiently within the intracranial blood vessel such that a first portion of an electrospun cover disposed on an entire outer surface of the stent is disposed directly against a neck of the aneurysm, the first portion having a first porosity to blood flow and at least one second portion of the membrane is disposed adjacent to and not directly over the aneurysm, the at least one second portion having a second porosity to blood flow greater than the first porosity.

It is understood that various configurations of the subject technology will become apparent to those skilled in the art from the disclosure, wherein various configurations of the subject technology are shown and described by way of illustration. As will be realized, the subject technology is capable of other and different configurations and its several details are capable of modification in various other respects, all without departing from the scope of the subject technology. Accordingly, the summary, drawings and detailed description are to be regarded as illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments are discussed in detail in conjunction with the Figures described below, with an emphasis on highlighting the advantageous features. These embodiments are for illustrative purposes only and any scale that may be illustrated therein does not limit the scope of the technology disclosed. These drawings include the following figures, in which like numerals indicate like parts.

FIG. 1A illustrates a portion of a blood vessel having an aneurysm, in accordance with some embodiments;

FIG. 1B illustrates an intravascular flow diverter located across the neck of an aneurysm.

FIG. 2 illustrates a microcatheter disposed within the blood vessel and near the aneurysm, in accordance with some embodiments;

FIG. 3 illustrates an intravascular flow diverter disposed within the blood vessel and immediately against the aneurysm, in accordance with some embodiments;

FIG. 4 illustrates a magnified view of a portion of the intravascular flow diverter of FIG. 3 , in accordance with some example embodiments;

FIG. 5A illustrates a cross-section of a first embodiment of the intravascular flow diverter of FIG. 3 , in accordance with some example embodiments;

FIG. 5B illustrates a cross-section of a second embodiment of the intravascular flow diverter of FIG. 3 , in accordance with some example embodiments;

FIG. 5C illustrates a cross-section of a third embodiment of the intravascular flow diverter of FIG. 3 , in accordance with some example embodiments;

FIG. 6 illustrates a flowchart related to a method of using an intravascular flow diverter, in accordance with some example embodiments; and

FIG. 7 illustrates a flowchart related to a method of manufacturing intravascular flow diverters, in accordance with some example embodiments.

DETAILED DESCRIPTION

The following description and examples illustrate some exemplary implementations, embodiments, and arrangements of the disclosed invention in detail. Those of skill in the art will recognize that there are numerous variations and modifications of this invention that are encompassed by its scope. Accordingly, the description of a certain example embodiment should not be deemed to limit the scope of the present invention.

Definitions

Collapsed Configuration— A device is in a collapsed configuration when it is sheathed proximate to and inside a distal end of a catheter ready for use in an endovascular surgical procedure.

Expanded Configuration— A device is in an expanded configuration when unsheathed outside the vasculature such that outward expansion of the sidewall is unconstrained by any surrounding walls. For flow diverters that are manually expanded by the surgeon, the expanded configuration is obtained when the flow diverter is manually expanded to its maximum intended diameter for normal use.

Deployed Configuration— A device is in the deployed configuration when unsheathed and with its side wall in contact with the inner wall of a vessel. A deployed configuration may have a smaller diameter for the sidewall than an expanded configuration depending on the size of the vessel in which the device is deployed. A device in the deployed configuration is typically close to but not fully in the expanded configuration.

Frame—One or more struts forming a structural scaffold defining a device sidewall configured to conform to the inner surface of a vessel segment when the device is in a deployed configuration. An arrangement of metal wires is a common implementation of struts for a frame.

Frame Porosity—The fractional open area of a selected portion of the sidewall defined by the struts of the device when the device is in a deployed configuration. The frame porosity may vary in different portions of a sidewall. Thus, for a given selected portion of a frame sidewall, the frame porosity is the total area of a selected portion of a sidewall minus the area of the struts defining the selected portion of the sidewall, divided by the total area of the selected portion of the sidewall when the device is in an expanded configuration.

Cover— A film or membrane connecting two or more struts of a frame and extending over some or all of the open area of the sidewall defined by the struts of the frame.

Cover Porosity—The fractional open pore area of a selected portion of a cover membrane when the device is in an expanded configuration. Cover porosity may vary in different portions of a sidewall that is covered by the membrane.

Pore Size—The size of a given pore is defined to be the diameter of an inscribed circle with three points of contact with the actual boundary of the given pore.

Cover Porosity Distribution—The cover porosity in a selected region of a cover may be distributed among groups of pores having particular pore characteristics, usually size characteristics. For example, a cover with 30% porosity may have a certain fraction of that porosity contributed by pores with a defined size range. The cover porosity distribution refers to a characterization of the amount of total porosity contributed by pores with a defined set of one or more properties.

Cover Permeability—Cover permeability is a qualitative or quantitative measure of the ability of different substances to pass through the cover when the device is in normal use in a vessel. Cover permeability is affected by several different aspects of a cover, including cover porosity and porosity distribution with respect to different size components of blood and/or particles in blood as well as the chemical properties of the cover material with respect to the chemical properties of different components of blood and/or particles in blood. Cover permeability to various blood components can also be affected by local flow and pressure conditions at the site of implantation in a vessel. The characteristics of the fluid flows encountered during use of the devices described herein where porosity and permeability are relevant device properties will be apparent from the context, and typically involve blood flow through the otherwise unobstructed ostia of intracranial blood vessels and/or necks of intracranial aneurisms over or across which the device is to be applied.

Electrospinning— A technique for depositing a layer of fibers onto a target surface that involves expelling a jet of polymer solution from an orifice in a reservoir to the target surface under the influence of an electric field. By moving the orifice and/or the target surface during the electrospinning process, polymer fibers and fibrous polymer layers and mats having a variety of characteristics can be created. A fiber or fibrous polymer layer or mat so deposited is referred to herein as “electrospun.” A variety of electrospinning techniques and materials suitable for electrospinning are described in paragraphs [0061] to [0077] of U.S. Patent Publication 2018/0161185 to Kresslein et al., which paragraphs are incorporated herein by reference.

The present disclosure relates to intravascular flow diverters and related methods of using and/or manufacturing the same. Several example embodiments of such intravascular flow diverters, and related methods, will now be described in connection with one or more figures.

Endovascular repair of fusiform aneurysms or bifurcation aneurysms is difficult due to complex flow geometries, side branching blood vessels at the bifurcation and the potential for perforating blood vessels that it is desirable to preserve. Accordingly, a need exists for improved intravascular flow diverters and related methods of using and/or manufacturing the same.

FIG. 1A illustrates a portion of a blood vessel 100. Artery 100 is illustrated as including one or more branching blood vessels 130 and an aneurysm 120, shown bulging beyond adjacent portions of blood vessel 100. FIG. 1A illustrates blood flow through the vessel 110 in the region around the aneurysm 120. In many cases, especially for wider necked aneurysms, some of the vessel blood flow 150 past the aneurysm neck is diverted into the aneurysm as aneurysm inflow 155, where it may circulate backwards and then re-enter the vessel flow 150 as aneurysm outflow 165. This intrasaccular circulation pushes outward on the aneurysm wall, causing expansion and possibly rupture. Endovascular repair of fusiform aneurysms or bifurcation aneurysms is difficult due to complex flow geometries, side branching blood vessels at the bifurcation, and the potential for perforating blood vessels with blood flows 151, 53 that are desirable to preserve.

Treatments for such types of aneurysms 120 can involve the use of flow diverters to bypass the diseased area. One contemporary treatment involves the use of a Medtronic's Pipeline flow diverter, having 64×0.001-inch diameter wires in a dense braid, configured to bridge over aneurysm 120. This is illustrated generally in FIG. 1B. Resistance to blood flow through the sidewall of such a pipeline flow diverter 270 is provided by this very dense wire braiding. However, this very dense wire braiding, in addition to such wires being constructed from cobalt chromium wire, can result in such pipeline flow diverters being very difficult to deploy. Additionally, to completely occlude flow to some such aneurysms 120, several such pipeline flow diverters often need be deployed concentrically within one another to achieve the desired inflow stasis to aneurysm 120. This makes for a costly and complicated procedure.

For these reasons and others, a need exists for improved flow diverters for aneurysm treatment and related methods of using and/or manufacturing the same. Accordingly, in some embodiments described herein, an intravascular flow diverter for treating an aneurysm of a blood vessel is provided. The diverter includes a stent including a plurality of wires coiled to form an expandable structure. The diverter includes a membrane disposed on an entire outer surface of the stent. The membrane includes a first portion configured to be disposed directly against a neck of the aneurysm. The membrane includes at least one second portion configured to be disposed adjacent to and not directly over the aneurysm. The first portion has a first porosity to blood flow, and the second portion has a second porosity to blood flow greater than the first porosity, at least one of the at least one second portions. Common locations for intracranial aneurysms include the communicating arteries, the internal carotid arteries, and the middle cerebral artery. The devices described herein can, for example, be used in these arteries.

In some other embodiments, a method for utilizing an intravascular flow diverter to treat an aneurysm of a blood vessel is provided. The method includes disposing the intravascular flow diverter within a microcatheter. The method includes threading the microcatheter through the blood vessel to a location of the aneurysm. The method includes removing the intravascular flow diverter from a distal end of the microcatheter such that a stent of the intravascular flow diverter, including a plurality of wires coiled to form an expandable structure, expands sufficiently within the blood vessel that a first portion of a membrane disposed on an entire outer surface of the stent is disposed directly against a neck of the aneurysm, and that at least one second portion of the membrane is disposed adjacent to and not directly over the aneurysm. The first portion has a first porosity to blood flow, and the at least one second portion has a second porosity to blood flow greater than the first porosity.

In some other embodiments, a method of manufacturing an intravascular flow diverter configured for treating an aneurysm of a blood vessel is provided. The method includes coiling a plurality of wires to form an expandable stent. The method includes disposing a membrane on an entire outer surface of the stent such that the membrane includes a first portion configured to be disposed directly against a neck of the aneurysm, and at least one second portion having a second porosity to blood flow greater than the first porosity and being configured to be disposed adjacent to and not directly over the aneurysm. having a first porosity to blood flow and being

Improvements to intravascular flow diverters as described herein may include a stent comprising a self-expanding and/or balloon expandable braid of wires 420 (which may be constructed from known techniques including, but not limited to, braiding and/or laser cutting) and coated with a thin membrane 410 comprising one or more portions 310, 320 a and 320 b having one or more desired porosities. Particulars of such an intravascular flow diverter 300 will be described in more detail in connection with at least FIGS. 3-5C.

As illustrated in FIG. 2 , such a flow diverter 300, comprising such a collapsible, collapsed stent and thin membrane, may be disposed within a microcatheter 200 and the microcatheter 200 threaded through blood vessel 100 until flow diverter 300 is disposed immediately adjacent aneurysm 120 with a goal of eliminating blood flow into aneurysm 120 and, thereby, reducing stress induced on a wall of aneurysm 120.

Once properly disposed immediately adjacent aneurysm 120 within blood vessel 100, the stent of flow diverter 300 may be allowed to self-expand under bias from the plurality of braided wires 420 (see, e.g., FIGS. 4-5C) and/or may be manually expanded utilizing an expansion balloon disposed within at least a portion of the collapsed stent (not shown in the figures), for example as illustrated in FIG. 3 .

As illustrated in FIG. 3 , intravascular flow diverter 300 may comprise a first portion 310 configured to be disposed directly over a neck of aneurysm 120. First portion 310 has a first porosity which prevents the circulating blood inflow 155 and outflow 166. This can be accomplished by, for example, depositing a relatively thick multilayer mat of electrospun fibers onto the stent frame in this region, essentially eliminating the ability of significant numbers of pores to span the thickness of the cover, producing, e.g., 0-0.05 (5%) porosity.

In other embodiments, it has been found that this inflow 155 and outflow 165 blocking function can be provided with membranes of surprisingly high porosities and large pore sizes. Generally, to generate a membrane that has low permeability to inflow 155 and outflow 165 in the presence of vessel flow 150, porosity and pore size should be appropriately balanced. Higher total porosities require smaller pore sizes, while lower porosities can have large pore sizes while maintaining the desired inflow 155 and outflow 165 suppression. This may be evaluated in a more quantitative manner by considering the product of median pore size times total fractional porosity as a characterization of cover porosity distribution. For advantageous flow diverter cover membranes, this product may be in the range of 0.5 to 50, with 5 to 20 having been found particularly suitable. For example, a suitable membrane may have a total porosity of 0.05 to 0.5 and a median pore size between 10 and 100 microns. In one implementation, a membrane with a porosity of 0.3 to 0.6 and a median pore size between 20 and 30 is utilized. In another implementation, a membrane with a total porosity between 0.05 and 0.15 and a median pore size between 30 and 100 microns is utilized. In another implementation, a membrane with a total porosity between 0.15 and 0.25 and a median pore size between 20 and 80 microns is utilized. In any of the implementations described herein, the pore size range may be from 5 to 400 microns, 5 to 200 microns, or 5 to 100 microns, wherein outliers outside of these ranges that do not significantly contribute the total porosity of the cover (e.g. less than 5% of the total porosity) are ignored.

In some embodiments, intravascular flow diverter 300 may further comprise one or more second portions 320 a, 320 b adjacent to first portion 310 and configured to allow for increased blood flow through side branches 130 of blood vessel 100 as compared to the reduced or substantially eliminated blood flow through first portion 310 and into aneurysm 120. Second portion(s) 320 has a second porosity that is greater than the first porosity of first portion 310 (e.g., 0.05-0.4 porosity). In some embodiments, one of second portions 320 may have a different porosity from either first portion 310 or the other second portion 320. Accordingly, flow diverter 300 may be configured to address side-wall aneurysms, bifurcation aneurysms, and fusiform aneurysms.

An electrospun stent cover membrane having porosity and permeability suitable for accomplishing one or more of these functions is described in paragraphs [0092] through [1013] of US Published Patent Application 2021/0052360, which paragraphs are incorporated herein by reference.

As illustrated in FIG. 4 , flow diverter 300 comprises a plurality of wires 420 braided around one another. For example, in some embodiments, each of wires 420 may be coiled into a collapsible and expandable, substantially helical shape or structure configured to have a predetermined length L₁ (e.g., approximately 0.79 inches or 20 mm, although any other suitable length is also contemplated) and a predetermined maximum diameter D₁ (e.g., approximately 0.18 inches or 4.5 mm, although any other suitable diameter is also contemplated) when fully expanded. In some such embodiments, each wire 420 is offset from adjacent wires 420 by a predetermined spacing L₃. In some embodiments, each of wires 420 may have a predetermined pitch L₂ (i.e., each loop or winding of a particular one of wires 420 extends predetermined length L₂ (e.g., approximately 0.18 inches or 4.5 mm, although any other suitable length is also contemplated) along a length of extension of flow diverter 300). In some such embodiments, the spacing L₃ may be determined as the result of dividing pitch L₂ of wires 420 by a number of those wires that are wound in a same direction. For example, in some embodiments, a subset (e.g., 8 of the plurality of wires 420) of the plurality of wires 420 are wound in a clockwise direction, while another subset of the plurality of wires 420 (e.g., another 8 of the plurality of wires 420) are wound in a counterclockwise direction. Accordingly, where subsets of wires 420 are wound in opposite directions from one another, one subset of wires 420 will overlap the other subset of wires 420 at multiple points along the predetermined length L₁.

In some embodiments, the frame is configured to elongate while collapsing to, thereby, minimize a collapsed diameter of the frame. The above-described geometries of wires 420 advantageously provide for easy, unobstructed expansion of flow diverter 300 in vivo. In some embodiments, wires 420 comprise super-elastic nitinol. In some other embodiments, a cobalt chromium may be used. In yet other embodiments, a nitinol shape memory alloy may be used. However, the present disclosure is not so limited and wires 420 may comprise any suitably flexible, expandable and compressible material.

As most easily seen in any of FIGS. 5A-5C, each of wires 420 may be further coated with a polymer 510 which may be a dip coating configured to substantially reduce or minimize metal exposure to the blood. The dip coating can also bind the wires together at the crossing points. In some embodiments, polymer 510 comprises an elastomeric polymer.

As further illustrated in FIG. 4 , flow diverter 300 comprises a membrane 410 disposed on at least a portion of the outer surface, typically an entire outer surface, e.g., substantially around an entire perimeter, of flow diverter 300 and along the entire length of extension L₁. For example, in some embodiments, membrane 410 has a substantially cylindrical form when the entirety of flow diverter 300 is disposed parallel to the length of extension L₁, as shown in FIG. 4 . Membrane 410 may provide support for the underlying expanded frame of wires 420 as well as a near or substantially impermeable layer that, advantageously, has a very thin construction, for example having a thickness Ti, as a result of an electrospinning process utilized to form membrane 410. The above-mentioned dip coating can provide a good bond between the electrospun membrane and the frame.

Membrane 410 providing such support, as well as this near impermeable layer, work together to allow a reduction in a number of wires 420 (e.g., 6, 8, 12 or 16 of wires 420) needed for construction and effective operation, for example compared to the Medtronic pipeline flow diverter (e.g., having and requiring 64 wires). For example, whereas such Medtronic pipeline flow diverters rely on the density and close proximity of the many (e.g., 64) individual wires to provide sufficient support to the blood vessel wall and to also provide sufficiently low porosity to prevent blood flow to the aneurysm, at least some of the requisite support to the wall of blood vessel 100 and the majority of the requisite low permeability of flow diverter 300 are provided by cover membrane 410.

Cover 410 may provide support for the underlying expanded frame of struts 640 while also possessing a very thin construction. A cover membrane 410 providing such support allows a reduction in a number of wires 420 needed for construction and effective operation, compared conventional devices not comprising such a membrane. The cover membrane allows an increase in frame porosity. In some embodiments, the frame porosity over a majority, substantially all, or all of its overall length is greater than 90%, preferably greater than 93%, more preferably greater than 95%.

This reduction in strut area (increase in frame porosity) also advantageously reduces device mass per unit length, delivery profile, longitudinal stiffness of, and radial force exerted by, device 300 during navigation to aneurysm 120 in the delivery system. All of these improvements separately and collectively allow for easier tracking into the vasculature and improved delivery and deployment of device(s) 300. This is especially true, and advantageous, for applications to smaller and/or tortious blood vessels, such as those of the brain, where the ratio of collapsed-to-appropriately deployed radii of device(s) may be much smaller than for applications to larger blood vessels, such as the aorta.

This reduction in wire number also advantageously reduces a delivery profile and longitudinal stiffness of, as well as a radial force exerted by, diverter 300 during navigation to aneurysm 120 in the delivery system. All of these improvements separately and collectively allow for easier tracking into the vasculature and improved delivery and deployment of diverter 300. This is especially true, and advantageous, for applications to smaller and/or tortious blood vessels, such as those of the brain, where the ratio of collapsed-to-appropriately deployed radii of diverter 300 may be much smaller than for applications to larger blood vessels, such as the aorta.

Moreover, the reduced number of wires 420 also provides more uniform porosity across the neck of a curve of diverter 300 at least because the smaller number of wires crowd to a comparatively lesser degree on the inside of such curves. And, because porosity along a length of diverter 300 is largely controlled by the porosity and/or permeability of membrane 410, the porosity and/or permeability of membrane 410 can be tailored to allow very low or substantially no blood flow through areas of membrane 410 immediately over or against the diseased blood vessel wall of aneurysm 120 (see, e.g., the portion of membrane 410 shown in FIG. 4 forming first portion 310 shown in FIG. 3 ) to, thereby, allow clots to form, organize and scar over to produce an effective long-term treatment, while simultaneously allowing substantially increased blood flow to or through areas of membrane 410 adjacent to but not over or directly against the diseased blood vessel wall of aneurysm 120 (see, e.g., the portions of membrane 410 forming the lateral second portion(s) 320 in FIG. 3 ) to, thereby, allow sufficient blood flow through side branches 130 of blood vessel 100.

Accordingly, in some embodiments, a density and/or a porosity of membrane 410 may be tuned to have different or variable values at different locations and, thereby, provide for the relatively high porosity of second portion(s) 320 (for positioning adjacent side branches 130) and for the relatively low porosity first portion 310 (for positioning at aneurysm 120, where isolation from blood flow and clotting external to the stent should be promoted). In such embodiments, areas of blood vessel 100 having perforating vessels or side branches 130 that require maintained blood flow advantageously remain viable by virtue of the increased blood flow through second portion(s) 320 of membrane 410. The above-described advantages may also directly reduce a need for physicians to use multiple flow diverters to achieve stasis of blood flow into aneurysm 120.

Another advantage of membrane 410 being applied to the stent formed from wires 420 is that the porosity, and therefore flow control, achieved by membrane 410 will advantageously allow fewer sizes of diverter 300 to be made available and/or used compared to existing flow diverters, all of which have fairly narrow ranges of vessel diameters for which each size is effective at segregating blood flow. For example, traditional wire braids are generally provided in ¼ mm increments while, at least in some embodiments, flow diverter 300 may be made available in sizes with much larger increments, e.g., 1.0 to 1.5 mm, thereby allowing 4-6 fewer sizes of diverters 300 than compared to traditional wire braid stents.

Additionally, flow diverter 300 may have an improved ability for use with coils, or intrasaccular flow diverters. For example, in the event of inadvertent rupture of an aneurysm while using flow diverter 300, in combination with such coils or intra-saccular flow diverters, flow diverter 300 provides additional hemostasis via membrane 410 compared to traditional dense wire braid stents.

It is also contemplated that wires 420 may have one of a variety of different thicknesses, according to requirements of a desired application. FIGS. 5A-5C illustrates cross-sections of first through third example embodiments of intravascular flow diverter 300, for example, as viewed along a cutline A-A′ shown in FIG. 4 . Each of the embodiments of FIGS. 5A-5C may be substantially similar to one another, except each utilizes wire 420 having a different diameter and, therefore, each illustrated embodiment of diverter 300 also comprises a respective minimum collapsed diameter.

As illustrated in FIG. 5A, wires 420 may have an outside diameter of approximately 0.002 inches, and diverter 300 may, accordingly, be configured to have a minimum contracted diameter D₂ (e.g., 0.011 inches) and the maximum expanded diameter D₁.

As illustrated in FIG. 5B, wires 420 may have an outside diameter of approximately 0.0015 inches and diverter 300 may, accordingly, be configured to have a minimum contracted diameter D₃ (e.g., 0.008 inches) and the maximum expanded diameter D₁.

As illustrated in FIG. 5C, wires 420 may have an outside diameter of approximately 0.001 inches, and diverter 300 may, accordingly, be configured to have a minimum contracted diameter D₄ (e.g., 0.006 inches) and the maximum expanded diameter D₁.

The example orientation of wires 420 in the collapsed state illustrated in each of FIGS. 5A-5C comprises an innermost subset of 8 threads and an outermost subset of 8 threads. Each of the innermost threads is disposed in direct contact with each of two adjacent threads of the innermost subset and one thread of the outermost subset. A center of each of the outermost threads is radially in-line with both a center of the frame's cross section and a center of the corresponding inner thread with which the outermost thread is in direct contact.

Example Method(s) of Use

The disclosure now turns to FIG. 6 , which illustrates a flowchart 600 related to an example method for utilizing an intravascular flow diverter 300, as described anywhere in this disclosure.

Although the method(s) disclosed herein comprise(s) one or more steps or actions for achieving the described method(s), such steps and/or actions may be interchanged with one another, and/or a subset of these steps and/or actions may be used, without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. One or more additional steps not specifically described herein may also be included.

Step 602 includes disposing the intravascular flow diverter within a microcatheter. For example, as previously described in connection with at least FIG. 2 , intravascular flow diverter 300 can be disposed within microcatheter 200.

Step 604 includes threading the microcatheter through the blood vessel to a location of the aneurysm. For example, as previously described in connection with at least FIG. 2 , microcatheter 200 can be threading through blood vessel 100 to a location of aneurysm 120.

Step 606 includes removing the intravascular flow diverter from a distal end of the microcatheter such that a stent of the intravascular flow diverter, comprising a plurality of wires coiled to form an expandable structure, expands sufficiently within the blood vessel that a first portion of a membrane disposed on an entire outer surface of the stent is disposed directly against a neck of the aneurysm, the first portion having a first porosity to blood flow, and at least one second portion of the membrane is disposed adjacent to and not directly over the aneurysm, the at least one second portion having a second porosity to blood flow greater than the first porosity.

For example, as previously described in connection with at least one of FIGS. 2-5C, intravascular flow diverter 300 can be removed from a distal end of microcatheter 200 (see, e.g., FIG. 2 ) such that a stent of intravascular flow diverter 300, comprising wires 420 coiled to form an expandable structure, expands sufficiently within blood vessel 100 that first portion 310 of membrane 410 is disposed directly against a neck of aneurysm 120, and at least one second portion 320 of membrane 410 is disposed adjacent to and not directly over aneurysm 120. First portion 310 has a first porosity to blood flow and second portion(s) 320 have a second porosity to blood flow greater than the first porosity.

In some embodiments, a method related to flowchart 600 may include an optional step 608 of expanding the plurality of wires by expanding a balloon from within the substantially helical shape. For example, as previously described in connection with at least one of FIGS. 2-5C, where wires 420 are not configured to self-expand under their own self-bias, a balloon may be expanded from within the substantially helical shape of wires 420.

In some embodiments, the expandable structure comprises each of plurality of wires 420 wound in a substantially helical shape. In some embodiments, each of wires 420 comprises a plurality of helical loops, each having a predetermined pitch L₂. In some embodiments, a first subset of wires 420 are wound in a clockwise direction and a second subset of wires 420 are wound in a counterclockwise direction. In some embodiments, each of wires 420 is offset from at least one adjacent wire 420 by a predetermined spacing L₃. In some embodiments, the plurality of wires is one of 6 wires, 8 wires, 12 wires and 16 wires. In some embodiments, wires 420 are configured to self-expand under a self-bias once intravascular flow diverter 300 is removed from microcatheter 200. In some embodiments, threading microcatheter 200 through blood vessel 100 to a location of aneurysm 120 comprises disposing at least one of the at least one second portions 320 directly over a side branch 130 of blood vessel 100. In some embodiments, the first porosity is sufficiently low that, when intravascular flow diverter 300 is properly disposed within blood vessel 100, first portion 310 of membrane 410 is configured to allow substantially no blood flow therethrough to, thereby, allowing a clot to form and ultimately scar over at aneurysm 120. In some embodiments, the second porosity is sufficiently high that, when intravascular flow diverter 300 is properly disposed within blood vessel 100, at least one of the at least one second portions 320 of membrane 410 are configured to allow substantial blood flow therethrough and directly into side branch 130 of blood vessel 100. In some embodiments, each of wires 420 has a diameter of one of approximately 0.002 inches, approximately 0.015 inches, and 0.001 inches (see, e.g., FIGS. 5A-5C). In some embodiments, intravascular flow diverter 300 has a minimum outside diameter D₂, D₃, D₄ of one of approximately 0.011 inches, approximately 0.008 inches, and approximately 0.006 inches when the expandable structure of the stent is fully collapsed (see, e.g., FIGS. 5A-5C). In some embodiments, intravascular flow diverter 300 has a maximum outside diameter D₁ of approximately 0.18 inches when the expandable structure of the stent is fully expanded. In some embodiments, a substantial majority of an aggregate porosity of intravascular flow diverter 300, at first and second portions 310, 320 of membrane 410, is derived from the first and second porosities of membrane 410 at the respective first and second portions 310, 320.

Example Methods of Manufacture

The disclosure now turns to FIG. 7 , which illustrates a flowchart 1000 related to an example method of manufacturing an intravascular flow diverter, as described anywhere in this disclosure.

Although the method(s) disclosed herein comprise(s) one or more steps or actions for achieving the described method(s), such steps and/or actions may be interchanged with one another, and/or a subset of these steps and/or actions may be used, without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. One or more additional steps not specifically described herein may also be included.

Step 702 includes coiling (e.g. looping, braiding, joining, or otherwise arranging) a plurality of wires to form an expandable stent. For example, as previously described in connection with at least one of FIGS. 2-5C, coiling wires 420 may be coiled to form an expandable stent.

Step 704 includes disposing a membrane on an entire outer surface of the stent such that the membrane comprises a first portion having a first porosity to blood flow and being configured to be disposed directly against a neck of the aneurysm, and at least one second portion having a second porosity to blood flow greater than the first porosity and being configured to be disposed adjacent to and not directly over the aneurysm.

For example, as previously described in connection with at least one of FIGS. 2-5C, membrane 410 may be disposed on an entire outer surface of the stent such that membrane 410 comprises first portion 310 having a first porosity to blood flow and being configured to be disposed directly against a neck of aneurysm 120, and at least one second portion 320 having a second porosity to blood flow greater than the first porosity and being configured to be disposed adjacent to and not directly over aneurysm 120.

In some embodiments, coiling wires 420 comprises winding each of wires 420 into a substantially helical shape. In some embodiments, wherein each of wires 420 are wound into the substantially helical shape such that each of a plurality of helical loops has a predetermined pitch L₂. In some embodiments, a first subset of wires 420 are wound in a clockwise direction and a second subset of wires 420 are wound in a counterclockwise direction. In some embodiments, each of wires 420 is offset from at least one adjacent wire 420 by a predetermined spacing L₃. In some embodiments, the plurality of wires 420 is one of 6 wires, 8 wires, 12 wires and 16 wires. In some embodiments, wires 420 are configured to self-expand under a self-bias. In some embodiments, wires 420 are configured to expand under influence of a balloon configured to be expanded from within the substantially helical shape. In some embodiments, intravascular flow diverter 300 is configured to be disposed, in a collapsed form, within microcatheter 200 that is configured to be threaded through blood vessel 100 to a location of aneurysm 120 (see, e.g., FIG. 2 ). In some embodiments, at least one of the at least one second portions 320 is configured to be disposed directly over side branch 130 of blood vessel 100. In some embodiments, the first porosity is sufficiently low that, when intravascular flow diverter 300 is properly disposed within blood vessel 100, first portion 310 of membrane 410 is configured to allow substantially no blood flow therethrough to, thereby, allow a clot to form and ultimately scar over at aneurysm 120. In some embodiments, the second porosity is sufficiently high that, when intravascular flow diverter 300 is properly disposed within blood vessel 100, at least one of the at least one second portions 320 of membrane 410 are configured to allow substantial blood flow therethrough and directly into side branch 130 of blood vessel 100. In some embodiments, each of wires 420 is provided to have a diameter of one of approximately 0.002 inches, approximately 0.015 inches, and 0.001 inches (see, e.g., FIGS. 5A-5C). In some embodiments, intravascular flow diverter 300 is configured to have a minimum outside diameter D₂, D₃, D₄ of one of approximately 0.011 inches, approximately 0.008 inches, and approximately 0.006 inches when the expandable structure of the stent is fully collapsed (see, e.g., FIGS. 5A-5C). In some embodiments, intravascular flow diverter 300 is configured to have a maximum outside diameter D₁ of approximately 0.18 inches when the expandable structure of the stent is fully expanded (see, e.g., FIGS. 5A-5C). In some embodiments, a substantial majority of an aggregate porosity of intravascular flow diverter 300, at the first and second portions 310, 320 of membrane 410, is derived from the first and second porosities of membrane 410 at the respective first and second portions 310, 320. In some embodiments, each of wires 420 comprises at least one of a super-elastic nitinol, cobalt chromium, and a nitinol shape memory alloy.

General Interpretive Principles for the Present Disclosure

Various aspects of the novel systems, apparatuses, and methods are described more fully hereinafter with reference to the accompanying drawings. The teachings disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the novel systems, apparatuses, and methods disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, a system or an apparatus may be implemented, or a method may be practiced using any one or more of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such a system, apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect disclosed herein may be set forth in one or more elements of a claim. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses, or objectives. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.

With respect to the use of plural vs. singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

When describing an absolute value of a characteristic or property of a thing or act described herein, the terms “substantial,” “substantially,” “essentially,” “approximately,” and/or other terms or phrases of degree may be used without the specific recitation of a numerical range. When applied to a characteristic or property of a thing or act described herein, these terms refer to a range of the characteristic or property that is consistent with providing a desired function associated with that characteristic or property.

In those cases where a single numerical value is given for a characteristic or property, it is intended to be interpreted as at least covering deviations of that value within one significant digit of the numerical value given.

If a numerical value or range of numerical values is provided to define a characteristic or property of a thing or act described herein, whether or not the value or range is qualified with a term of degree, a specific method of measuring the characteristic or property may be defined herein as well. In the event no specific method of measuring the characteristic or property is defined herein, and there are different generally accepted methods of measurement for the characteristic or property, then the measurement method should be interpreted as the method of measurement that would most likely be adopted by one of ordinary skill in the art given the description and context of the characteristic or property. In the further event there is more than one method of measurement that is equally likely to be adopted by one of ordinary skill in the art to measure the characteristic or property, the value or range of values should be interpreted as being met regardless of which method of measurement is chosen.

It will be understood by those within the art that terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are intended as “open” terms unless specifically indicated otherwise (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.).

It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations).

In those instances where a convention analogous to “at least one of A, B, and C” is used, such a construction would include systems that have A alone, B alone, C alone, A and B together without C, A and C together without B, B and C together without A, as well as A, B, and C together. It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include A without B, B without A, as well as A and B together.”

Various modifications to the implementations described in this disclosure can be readily apparent to those skilled in the art, and generic principles defined herein can be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the disclosure is not intended to be limited to the implementations shown herein but is to be accorded the widest scope consistent with the claims, the principles and the novel features disclosed herein. The word “exemplary” is used exclusively herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable sub-combination. Moreover, although features can be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination can be directed to a sub-combination or variation of a sub-combination.

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. 

What is claimed is:
 1. An intravascular flow diverter for treating an aneurysm of an intracranial blood vessel, the intravascular flow diverter comprising: one or more wires forming a frame, wherein the frame has a collapsed configuration and an expanded configuration, wherein the frame is configured to transition in use from the collapsed configuration to a deployed configuration that substantially conforms to a shape of an inside surface of the intracranial blood vessel in the vicinity of the aneurysm; an electrospun cover disposed on at least a portion of the frame, the cover comprising: a first portion configured to be disposed against a neck of the aneurysm, the first portion of the cover having pores formed therein defining a first porosity thereof; and a second portion having a second porosity to blood flow greater than the first porosity, wherein the second portion is configured to be disposed adjacent to and not directly over the aneurysm.
 2. The intravascular flow diverter of claim 1, wherein the one or more wires are configured to self-expand under a bias from the plurality of wires.
 3. The intravascular flow diverter of claim 1, wherein the one or more wires are configured to expand under influence of a balloon configured to be expanded from within the frame.
 4. The intravascular flow diverter of claim 1, wherein the intravascular flow diverter is configured to be disposed, in a collapsed form, within a microcatheter that is configured to be threaded through the intracranial blood vessel to a location of the aneurysm.
 5. The intravascular flow diverter of claim 1, wherein the second portion is configured to be disposed directly over a side branch of the blood vessel.
 6. The intravascular flow diverter of claim 1, wherein the first porosity is sufficiently low that, when the intravascular flow diverter is properly disposed within the blood vessel, the first portion of the membrane is configured to allow substantially no blood flow therethrough to allow a clot to form and ultimately scar over at the aneurysm.
 7. The intravascular flow diverter of claim 1, wherein the second porosity is sufficiently high that, when the intravascular flow diverter is disposed within the blood vessel, the second portion of the cover is configured to allow substantial blood flow therethrough and directly into a side branch of the blood vessel.
 8. The intravascular flow diverter of claim 1, wherein each of the plurality of wires has a diameter of one of approximately 0.002 inches, approximately 0.015 inches, and 0.001 inches.
 9. The intravascular flow diverter of claim 1, wherein the intravascular flow diverter is configured to have a minimum outside diameter of one of approximately 0.011 inches, approximately 0.008 inches, and approximately 0.006 inches when the expandable structure of the stent is fully collapsed.
 10. The intravascular flow diverter of claim 1, wherein the intravascular flow diverter is configured to have a maximum outside diameter of approximately 0.18 inches when the expandable structure of the stent is fully expanded.
 11. The intravascular flow diverter of claim 1, wherein a substantial majority of an aggregate porosity of the intravascular flow diverter, at the first and second portions of the membrane, is derived from the first and second porosities of the membrane at the respective first and second portions.
 12. The intravascular flow diverter of claim 1, wherein each of the plurality of wires comprises at least one of a super-elastic nitinol, cobalt chromium, and a nitinol shape memory alloy.
 13. An intravascular flow diverter for treating an aneurysm of an intracranial blood vessel, the intravascular flow diverter comprising: one or more wires forming a frame, wherein the frame has a collapsed configuration and an expanded configuration, wherein the frame is configured to transition in use from the collapsed configuration to a deployed configuration that substantially conforms to a shape of an inside surface of the intracranial blood vessel in the vicinity of the aneurysm; an electrospun cover disposed on at least a portion of the frame, the cover comprising: a first portion configured to be disposed against a neck of the aneurysm, the first portion of the cover having pores formed therein defining a first porosity thereof; and a second portion distal to the first portion having a second porosity to blood flow greater than the first porosity, wherein the second portion is configured to be disposed adjacent to and not directly over the aneurysm; and a third portion proximal to the first portion having a third porosity to blood flow greater than the first porosity, wherein the third portion is configured to be disposed adjacent to and not directly over the aneurysm; wherein each of the one or more wires has a diameter of less than 0.002 inches, wherein the frame porosity over substantially the whole length of the frame is at least 93% in an expanded frame configuration, wherein the first porosity is less than 0.05 and the second porosity and the third porosities are each greater than 0.05.
 14. The intravascular flow diverter of claim 13, wherein the second porosity and the third porosity are each less than 0.4.
 15. The intravascular flow diverter of claim 13, wherein the expandable structure comprises each of the one or more wires wound in a substantially helical shape.
 16. The intravascular flow diverter of claim 15, wherein each of the one or more wires comprises a plurality of helical loops, each having a predetermined pitch.
 17. The intravascular flow diverter of claim 16, wherein a first subset of the one or more wires are wound in a clockwise direction and a second subset of the plurality of wires are wound in a counterclockwise direction.
 18. The intravascular flow diverter of claim 17, wherein each wire of the one or more is offset from at least one adjacent one of the plurality of wires by a predetermined spacing.
 19. The intravascular flow diverter of claim 13, wherein the one or more wires is one of 6 wires, 8 wires, 12 wires and 16 wires.
 20. The intravascular flow diverter of claim 13, wherein each of the plurality of wires has a diameter of one of approximately 0.015 inches and 0.001 inches.
 21. The intravascular flow diverter of claim 13, wherein the intravascular flow diverter has a minimum outside diameter of one of approximately 0.011 inches, approximately 0.008 inches, and approximately 0.006 inches when the expandable structure of the stent is fully collapsed.
 22. The intravascular flow diverter of claim 13, wherein the intravascular flow diverter has a maximum outside diameter of approximately 0.18 inches when the expandable structure of the stent is fully expanded.
 23. The intravascular flow diverter of claim 13, wherein a substantial majority of an aggregate porosity of the intravascular flow diverter, at the first and second portions of the membrane, is derived from the first and second porosities of the membrane at the respective first and second portions.
 24. The intravascular flow diverter of claim 13, wherein each of the plurality of wires comprises at least one of a super-elastic nitinol, cobalt chromium, and a nitinol shape memory alloy.
 25. A method of using an intravascular flow diverter to treat an aneurysm of an intracranial blood vessel, the method including: disposing the intravascular flow diverter within a microcatheter; threading the microcatheter through the intracranial blood vessel to a location of the aneurysm; and removing the intravascular flow diverter from a distal end of the microcatheter such that a stent of the intravascular flow diverter, comprising a plurality of wires coiled to form an expandable structure, expands sufficiently within the intracranial blood vessel that: a first portion of an electrospun cover disposed on an entire outer surface of the stent is disposed directly against a neck of the aneurysm, the first portion having a first porosity to blood flow, and at least one second portion of the membrane is disposed adjacent to and not directly over the aneurysm, the at least one second portion having a second porosity to blood flow greater than the first porosity.
 26. The method of claim 25, comprising expanding the intravascular flow diverter under a bias from the plurality of wires once the intravascular flow diverter is removed from the microcatheter.
 27. The method of claim 25, comprising expanding the plurality of wires by expanding a balloon from within the substantially helical shape.
 28. The method of claim 25, wherein threading the microcatheter through the intracranial blood vessel to a location of the aneurysm comprises disposing at least one of the at least one second portions directly over a side branch of the blood vessel.
 29. The method of claim 25, wherein the first porosity is sufficiently low that, when the intravascular flow diverter is properly disposed within the intracranial blood vessel, the first portion of the membrane is configured to allow substantially no blood flow therethrough to, thereby, allow a clot to form and ultimately scar over at the aneurysm.
 30. The method of claim 25, wherein the second porosity is sufficiently high that, when the intravascular flow diverter is properly disposed within the blood vessel, at least one of the at least one second portions of the membrane are configured to allow substantial blood flow therethrough and directly into a side branch of the intracranial blood vessel. 